Two-photon excitation fluorescence microscopy

Two-photon fluorescence microscopy is one of the most important recent inve ntions in biological imaging. This technology enables noninvasive study of biological specimens in three dimensions with submicrometer resolution. Two -photon excitation of fluorophores results from the simultaneous absorption of two photons. This excitation process has a number of unique advantages, such as reduced specimen photodamage and enhanced penetration depth. It al so produces higher-contrast images and is a novel method to trigger localiz ed photochemical reactions. Two-photon microscopy continues to find an incr easing number of applications in biology and medicine.